A lot of people recommend ... breaking-in a semiautomatic shotgun by firing four or five boxes of heavy loads through it. The break-in process smooths burrs in the action, lets metal parts wear in, and generally imroves the gun's performance. It's a good idea. After a little breaking in, some semiautos -- especially the newer models -- will perform impressive feats of functioning. A couple of summers ago I had a Browning Silver on extended loan. Atlhough the manual recommended nothing lighter than one ounce loads, it would cycle my 1200fps, ¾ ounce 12 gauge reloads all day long after I shot three or four boxes of heavy hunting loads through it.